Hello,
Here is my final post. I enjoyed this activity with the kids. The kids especially enjoyed working with the hydrophilic polymer spheres. They had lots of ideas about how to further test these.
I was shocked at how little the kids knew about excel. Very few of them knew how to create a data table, make calculations from the data and even fewer knew how to use it to make a graph.
I purchased the spheres from Educational Innovations, cheap and reusable.
I will enclose a sample of student work as a separate post.
Enjoy

Here is an example of the student's work.

Stacey,

I hadn't a clue what the hydrophilic polymer spheres were so I did a Google search to check it out. I found out that stuff comes in different shapes and sizes to begin with. Interesting material. Looks like it is almost gel like. Is it? I am sure the students were fascinated with trying different materials to see what the absorbtion rates would be. Apparently salt doesn't allow much absorption by the hydrophilic polymer spheres. Why is that?

Anne Marie

I bought the spheres from Educational Innovations.
The kids love the spheres, I did let them keep one each and then dehydrated the rest.
The spheres are fairly bouncy and the different absorptions affect the bounciness. I could even do a future experiment about how many bounces plain water, salt water, and sugar water absorptions sphere will complete before stopping.
This would tie into our gravitational potential energy.

I think the ions of the salt water inhibit the absorption of water. Since sugar does not ionize, I don't think it had much effect on the absorption rate.

Hi Stacy,
Thanks for sharing this great lesson idea. I plan to modify it and use it with my math class at the end of the year. I was fascinated by your results. According to Wikipedia "SAP (super absorbent polymers) may absorb 500 times its weight (from 30-60 times its own volume), but when put into a 0.9% saline solution, the absorbency drops to maybe 50 times its weight. I am thinking of using the SAP in disposable diapers for this investigation.